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EPO Boards of Appeal Approach to Partial Priorities

EPO DECISION T0260/14

Following the Decision of the Enlarged Board of Appeal at the EPO in G1/15 regarding partial priorities, the EPO Technical Boards of Appeal have started applying the principles from this decision when deciding whether claims should be entitled to partial priority. This case sets out a two-step test which we expect to be used by future Boards of Appeal when examining partial priorities.

The applications relate to compositions for dental impression materials.
Claim 1 of the granted patent read as follows:

"A dental impression material comprising a base paste and a catalyst
paste, wherein the base paste comprises at least one polymerizable
polyether material with a linear backbone having no side chains which
is selected from the group consisting of

a) polyethers with at least one aziridino group,

b) polyethers with at least one olefinically unsaturated group and a
compound with at least one SiH group and

c) polyethers with at least one olefinically unsaturated group and at
least one SiH group and

d) polyethers with at least one alkoxysilyl group;

e) polyethers with at least one olefinically unsaturated group

and 0.1 to 15% by weight of a fluidity improver, the fluidity improver
being a random copolyether of ethyleneoxide and at least one more
alkyleneoxide which is not ethylene oxide, the copolymer comprising at
least about 50% of structural elements from ethylene oxide as a
fluidity improver, the fluidity improver having a molecular weight Mw
in a range of 100 to 1900, and wherein the catalyst paste comprises at
least one initiator or catalyst or both for initiating or catalyzing
the polymerization of the at least one polymerizable polyether
material."

At opposition, the opponent argued that as claim 1 of the patent as granted
was different from claim 1 in the priority application, priority could not
be validly claimed. Consequently, the published priority document became
prior art under Art. 54(3) EPC and a working example disclosed in the
priority application anticipated claim 1 of the granted patent.

At appeal, the Technical Board of Appeal applied the Enlarged Board
Decision, G1/15. In applying the decision, they stated that there is a
two-step test to deciding whether claimed subject-matter can be entitled to
partial priority.

Firstly, it is necessary to determine what is disclosed in the priority
applications by applying the principles laid out in G2/98 (namely what is
clearly and unambiguously disclosed). In determining this, it is necessary
to look not only at the claims of the priority application but also at the
description.

Secondly, one must examine whether this subject-matter is encompassed by
the claim of the patent in question. As G1/15 is concerned with generic
“OR”-type claims, it is also essential to ensure that the claim in question
is such a type of claim. Therefore, the subject-matter disclosed in the
priority application must be alternative subject-matter by virtue of a
generic “OR”-type claim. Although it is not necessary whether the
subject-matter is expressly identified in the claims as an alternative, it
must be envisaged that numerous alternatives exist.

In this case, the subject-matter relied on by the opponent as anticipating
the claim was a working example. This working example clearly fell within
the scope of the disputed claim and it was accepted that the working
example was just one specific embodiment of the claim and that other
alternative examples with different variants were possible and would fall
within the scope of the claim.

Accordingly, the claim was entitled to partial priority and the priority
document was not considered to be novelty-destroying pursuant to Article
54(3) EPC.

At appeal, the Opponent submitted that the situation in this case was
distinguished from the case in G1/15, as in the present case, the scope of
at least one of the features in the claim of the patent was narrower than
the scope in the priority application. The priority application disclosed a
molecular weight for the fluidity improver of 100-3800, whereas in the
patent, claim 1 stated that its molecular weight was 100-1900. The Opponent
argued that in G1/15 the disclosure in the priority document was narrower
in all respects that the granted patent. The Board considered this issue
irrelevant as the question being addressed was whether the part of claim 1
which concerns the working example was entitled to claim priority from the
earlier application.